1. Field of the Invention
This invention relates generally to data processing systems and more particularly to magnetic media storage systems used in such data processing systems.
2. Description of Related Art
Many data processing systems include one or more central processors and one or more magnetic media storage systems. Typically, the magnetic medium comprises either a magnetic disk or a magnetic tape. Magnetic disk media storage systems, particularly, have been developed for use with particular machines according to particular data structures or formats. IBM mainframe computers constitute one such machine. UNIX-based or open systems constitute machines characterized by another diverse data structure.
For purposes of understanding this invention, one such characteristic is the relationships among a drive, the number of cylinders on a drive, the number of tracks in a cylinder, number of sectors in a track, the number of data blocks in a sector and the number of bytes in a data block. For example, Unix computers and the like operate with a data structure in which a data block comprises 512 bytes. Certain disk storage systems for Unix-based data processing systems, such as those supplied by the assignee of this invention, further arrange eight data blocks into one sector and eight sectors into one track.
Other computer systems exist that utilize host processors for operation with other, diverse data structures in which block sizes contain a different number of bytes. As one example, a host may operate with 2,088 bytes in a block. However, the market for magnetic disk storage devices for such data processing systems is limited, and the costs of adding such storage systems that are specifically designed for such data structures can be prohibitive. Likewise, rewriting applications to conform to another data structure is also prohibitive.
One might consider reformatting a standard device with the data structures characteristic of the host system. However, it has been found that this is difficult or impossible to accomplish primarily because magnetic disk storage devices themselves, even at the most basic levels, have been designed around standard data structures and can not be adapted to non-standard structures. Consequently, there has been no approach for integrating such standard magnetic disk storage systems into such non-standard data processing systems in a way that is transparent to input/output requests from a host with diverse data structures. However, as storage requirements increase, the demand for additional magnetic disk storage that operates with such hosts also increases.